This invention pertains to magnetic read heads adapted to read information from a magnetic stripe and, more particularly, to a magnetic read heads adapted with a fully integrated circuit (IC) component, the IC component being a mixed signal (analog and digital) circuit produced on a single silicon chip and being capable of converting the magnetic head signal into a digital signal for direct use by computer components.
Magnetic read heads have been used for many years for such diverse applications as playing back music and/or video signals from a magnetic medium, such as a tape or stripe, reading magnetic characters on the bottom of checks, and reading magnetically encoded information from magnetic stripes on credit cards, telephone calling cards, access badges, tickets, and the like. Generally, the heads of the prior art feature a magnetic pole piece having a precision gap at or near the point of contact with the media to be read. One or more coils of wire wound around the magnetic pole piece generate a voltage in response to a change in a magnetic field near the head gap. The electrical signal induced in the head is then amplified, filtered and eventually decoded to retrieve the information from the magnetic medium. Heretofore, magnetic read heads have generally been stand-alone structures. Only the pole piece, housing and winding have been packaged as a single device.
U.S. Pat. No. 3,612,835 for COMBINED OPTICAL AND MAGNETIC TRANSDUCER, issued Oct. 12, 1971 to Boley A. Andrews, et al., teaches a magnetic read head with an optical transducer installed within the head assembly. ANDREWS, however, teaches no electronic circuitry. Both the magnetic and the optical transducers generate small-amplitude analog signals which are unmodified within the head structure. In contradistinction, the magnetic head of the present invention includes decode electronics so that no analog, small-amplitude signals leave the head assembly. Rather a decoded, digital signal is presented at the output terminals of the read assembly, or an attached cable assembly.
U.S. Pat. No. 5,276,572 for MAGNETIC DISK APPARATUS, issued Jan. 4, 1994 to Kinoshita et al., teaches an electric circuit for controlling a magnetic head, the circuit being mounted on a flexible printed circuit, folded within an enclosure. Thus, integrated circuit components have been used on circuit boards, separate from the head assembly, as taught by KINOSHITA et al. The circuits were not mounted to the read head, but to a movable arm on springs with the flexible printed circuit used to interconnect the heads with pre-amplifier circuits mounted to the movable arm. Additional circuits were mounted in a, fixed location below the movable arm. A considerable distance is present between the head and any circuits.
U.S. Pat. No. 5,117,097 for KEY SYSTEM FOR A VEHICLE, issued May 26, 1992 to Takashi Kimura, et al., teaches a tuned resonant circuit packaged within a key structure. While not a magnetic read head, the KIMURA structure does include a pole piece (i.e., the protruding extension of the key structure) having a winding thereupon. Discreet inductive and capacitive elements are connected to the winding to form a resonant circuit. The inventive read head, on the other hand, encompasses a structure to read information from a magnetic stripe or the like and, using self-contained circuitry, to provide a digital output signal corresponding to the information on the magnetic stripe. The inventive head does not rely on a resonant circuit comprising inductive and/or capacitive elements connected to the read head winding.
U.S. Pat. No. 5,212,602 for MAGNETIC HEAD HAVING A FUSE WITHIN HEAD CASE, issued May 18, 1998 to Hidefumi Suzuki teaches a magnetic head with a fuse physically within the head structure. The fuse is connected in series with the read head and is used to permanently disable the read head at end-of-life to prevent fraudulent use of the head (e.g., forging credit cards). The inventive read head, however, contains no fuse or similar structure designed to disable the head. Rather, the inventive head features an on-board decode electronics package designed to convert low-level, analog signals read from a magnetic stripe into a digital output signal.
Finally, U.S. Pat. No. 5,450,263 for THIN FILM INDUCTORS, INDUCTOR NETWORK AND INTEGRATION WITH OTHER PASSIVE AND ACTIVE DEVICES, issued Sep. 12, 1995 to Chan M. Desaigoudar, et al. teaches a fabrication technique for forming thin-film inductors, capacitors, resistors and semiconductors on a thin substrate. These components, used in combination, are capable of constructing a multi-channel, magneto-resistive or similar type read head. The magnetic read head of the instant invention, however, is totally different. A physical coil of wire wound upon a pole piece, not a thin-film inductor, is used as a traditional inductive pickup. Additional circuitry within or near the head casing is used not as a part of the pickup portion of the head, but rather as an IC component to convert a low-level, analog signal induced in the read head winding into a digital output signal.
It is therefore an object of the invention to provide a read head for reading encoded information from a magnetic stripe or similar magnetic medium.
It is a further object of the invention to provide a read head having IC components packaged within the head casing or packaged as a monolithic part of the head, forming a unitary structure.
It is an additional object of the invention to provide a read head adapted to receive power, ground and control signals and to provide a digital output signal at a standard, predetermined signal level.
It is a still further object of the invention to provide a read head which provides a magnetic media detected signal.
It is yet another object of the invention to provide a read head with a low susceptibility to external electrical noise.
It is another object of the invention to provide a read head with a case and flex circuitry or other such interconnection means, to supply power to the head, receive decoded signals from the head, or transmit digital signals to the head.
It is a still further object of the invention to provide a hybrid read head with IC components which has a higher reliability and lower cost than do magnetic read heads with external decode electronics.
The present invention features a magnetic read head having built-in electronic decode circuitry in the form of IC components. No low-level, analog signals, which are generally highly susceptible to electrical noise, leave the head structure. Power and ground are provided to the hybrid head. This invention combines the head element and, attached inside or directly on the immediate head structure, an IC together as a single structure, to form a single integrated reading component. This reading component is spring mounted as a single unit in the mechanical structure. Digitized data corresponding to encoded information upon a magnetic stripe on a credit card, I.D. badge, or similar article is provided at output terminals, attached cables, or other interconnections. In addition, a data strobe signal is provided by the head. An optional magnetic media detected signal may also be provided.